Numerous designs have been used for toy and structural building blocks. Examples of the toy building blocks are disclosed in the patents to N. I. Paulson, U.S. Pat. Nos. 2,262,199, 3,405,479 and 3,481,068; G. Morin, U.S. Pat. No. 3,420,527; Yoshihiro Kishi, U.S. Pat. No. 3,570,170; Takashi Matsubayashi, et al., U.S. Pat. No. 3,605,322; C. O. Perry, U.S. Pat. No. 3,611,620; J. Pippet, U.S. Pat. No. 3,716,939; W. Schnabel, U.S. Pat. No. 3,717,946; J. B. De Vos, U.S. Pat. No. 3,822,499; G. Vogel, U.S. Pat. No. 3,862,512; J. A. Gale, U.S. Pat. No. 4,129,960 and Y. Chatani, et al., U.S. Pat. No. 4,306,373. An example of structural interconnecting blocks is shown in the patent to G. L. Hernandez, U.S. Pat. No. 4,060,952.
In each of the disclosures of these patents, building blocks are provided having structure for permitting the interconnection of the individual blocks. In each of these cases, the interconnection is by way of protrusions from one or more faces of the blocks which protrusions are received in apertures also provided in the blocks. The protrusions and receiving apertures are generally sized for a snug or interference fit to effect an interlocking force upon engagement of one block to another. By way of example only, in the patent to Y. Chatani, et al., U.S. Pat. No. 4,306,373, a frictional interconnecting toy block is provided having a male cylindrical coupler extending from selected sidewalls of a cube for engagement within a female receiving aperture. The male cylindrical couplers are sized to provide an interlocking fit upon engagement of the male coupler into the female coupler. In this arrangement, as is generally the case, upon interconnection of one block with another, the male coupler is completely received within the female coupler and is not viewable after interconnection.
Similar interconnecting blocks have been used as game pieces for use in playing games or solving puzzles defined by use of such blocks. Examples of such structures are shown in the patents to M. J. J. Sugden, U.S. Pat. No. 3,481,603; D. Wolf, U.S. Pat. No. 3,672,681; and to D. G. Henderson, U.S. Pat. No. 4,239,233.
In these patents, interconnecting blocks have either male or female coupling structures formed on one or more faces of the blocks for engagement with corresponding female or male coupling structures, respectively. In the patent to D. Wolf, cubes are formed with holes in the faces thereof and assembly of the cubes is achieved by using a tubular coupling member for insertion into the apertures of a pair of the playing pieces. In these structures, the coupling protrusions are also hidden from view upon assembly. Thus, these elements of the building blocks are not used as a part of the overall finished design and likewise are not intended for use as part of the puzzle or game associated with the assembly of the component blocks.